Compensation circuit for channel to channel crosstalk

Abstract

A circuit, for applying a potential to a charge electrode in a multiple jet ink jet printer to compensate for the cross talk charging effect of adjacent electrodes on the jet filament, includes a means for applying a catch potential or a print potential to the electrode. Means are provided for altering the print potential when one of two adjacent electrodes is supplied with a catch potential and means are provided for altering the print potential when both of the adjacent electrodes are supplied with a catch potential. The print potential is reduced by an amount sufficient to reduce the cross talk field from adjacent electrodes in the region of the jet to the same potential level as the jet filament. A transistor current source applies a large current to the charge electrode during catch operations such that the stray capacitance associated with the electrode is rapidly charged and the electrode is brought to the catch potential rapidly.

What is claimed is: 
     
       1. A circuit for applying a potential to a charge electrode in an ink jet printer having multiple jets, to compensate for the charging effect of adjacent electrodes, comprising: means for applying a catch potential or a print potential to the electrode for catch or print operations, respectively,   means for altering the print potential applied to the electrode when one of two adjacent electrodes is supplied with a catch potential, and   means for altering the print potential applied to the electrode when both of the adjacent electrodes are supplied with a catch potential, such that the charging effect of adjacent electrodes is compensated.   
     
     
       2. A circuit for applying a print potential, first and second adjusted print potentials, or a catch potential to a charge electrode associated with one jet in a multiple jet printer, comprising: first data input means for receiving a data signal indicating a print or catch operation for the one jet,   second data input means for receiving data signals indicating print or catch operations for the jets adjacent the one jet,   first means, responsive to said first data input means, for applying a catch potential to the electrode,   second means, responsive to said first and second data input means, for applying a print potential to said electrode, and   third means, responsive to said first and second input means, for applying first or second adjusted print potentials to said electrode when one or more adjacent jets are being caught, respectively.   
     
     
       3. The circuit of claim 2 in which said first means comprises a transistor current source means for providing a large current to the charge electrode upon receipt by said first data input means of a data signal indicating a catch operation such that the charge electrode rapidly attains a catch potential. 
     
     
       4. A compensation circuit for adjusting the potential applied to a charge electrode associated with one ink jet in an ink jet printer to compensate for cross talk from adjacent electrodes, comprising: data input means for receiving data signals for the one charge electrode and the adjacent electrodes,   charge inducing potential means for applying a catch potential to the electrode,   first switch means for reducing the voltage applied to the electrode to a potential equal to that of the associated ink jet,   second switch means for reducing the potential on the electrode to a potential less than that of the jet by an amount sufficient to compensate for cross talk from one of said adjacent electrodes,   third switch means for reducing the potential on said electrode to a potential which will compensate for cross talk from two adjacent electrodes, and   digital logic means, responsive to said data input means, for switching said first, second, and third switch means such that the electrode is maintained at a potential which equalizes the cross talk fields from adjacent electrodes and prevents inadvertent charging of the drops in the jet.   
     
     
       5. The compensation circuit of claim 4 in which said charge inducing potential means for applying a catch potential to the electrode includes a transistor current source for applying a large current to the charge electrode such that stray capacitance associated with the electrode will be rapidly charged and the electrode will be brought to the catch potential rapidly. 
     
     
       6. A compensation circuit for use with an ink jet in an ink jet printer having multiple jets associated charge inducing electrodes to which print and catch potentials are applied, comprising: means for applying a print potential or a catch potential to an electrode in correspondence to the operation desired,   means for adjusting the potential applied to the electrode during print operations in a direction which will compensate for cross talk from adjacent electrodes by a predetermined amount when one of two adjacent jets is catching, and   means for adjusting the potential applied to the electrode when both of the adjacent jets are catching by an amount twice said predetermined amount.   
     
     
       7. In an ink jet printer having a moving print web upon which an image is to be formed,   means for generating a plurality of parallel jets of ink drops directed toward said moving web, said jets positioned in a row,   a plurality of charge electrodes, each of said plurality of electrodes positioned adjacent the region of drop formation of a respective one of said jets, and   means for generating a charge inducing potential for selectively charging said ink drops in each of said jets, the improvement comprising:   means, responsive to said means for generating a charge inducing potential, for selectively altering the potential of each of said charge electrodes when a charge inducing potential is not applied thereto such that the fields created in the region of jet drop formation by adjacent charge electrodes are reduced.